Replication of standard and defective Ross River virus in BHK cells: patterns of viral RNA and polypeptide synthesis.

Virus-specific macromolecule synthesis has been examined in BHK cells infected with Ross River virus. Unpassaged virus (R-0) and tenth-passage virus (R-10) have been compared. In infected cells R-0 generates i) 45S, 28S, 33S and 26S viral RNAs, ii) virus-specific precursor polypeptides of mol. wt. 127,000, 95,000 and 61,000 and iii) viral envelope proteins (mol. wts. 52,000 and 49,000) and nucleocapsid protein (mol. wt. 32,000). Thus in terms of virus-specific RNA and polypeptide synthesis, the replication of standard RRV is analogous to that of Semliki Forest virus and Sindbis virus. R-10 interferes with the replication of standard Ross River virus and generates large amounts of 19S and 24S defective RNA species; 45S and 26S RNA synthesis was not markedly affected. Defective RNAs are associated with RNAse-sensitive, 50S cytoplasmic particles which contain a variety of (mainly host) proteins but no nucleocapsid protein. No evidence for translation of defective RNAs was obtained. R-10 infection is also characterized by a relatively early shut down of host protein syntehsis and by a reduction in virus-specific polypeptide synthesis and nucleocapsid formation. The data suggest that defective Ross River virus interferes primarily at the translational level.